1. Field of the Invention
The present invention relates to the art of trailer to tractor hitch assemblies wherein the ball structure of the hitch assembly is designed to rock back and forth and thereby absorb travel occasioned lateral shocks.
2. Background of the Prior Art
Trailers are often attached to towing vehicles or tractors via a releasable mechanical coupling. One of the most popular couplings, especially for smaller trailers, is the so-called hitch ball coupling. In this arrangement, a hitch receiver is affixed to the frame of the tractor in appropriate manner. A draw bar, which is an elongated shaft member, is slidably inserted longitudinally into the hollow interior of the hitch receiver and a locking pin is passed through aligned opening pairs on each of the hitch receiver and the draw bar, thereby coupling the two elements together. The end of the pin is clipped. A mount arm extends from the draw bar such that a hitch ball extends upwardly from the mount arm. The hitch ball is removably fastened to the mount arm by providing the hitch ball with a downwardly depending threaded shank that passes through a bore on the mount arm with a locking nut attached to a distal end of the shank in order to hold the hitch ball onto the mount arm. The trailer is equipped with a ball receiver, which is a tongue member that has a cylindrical cavity designed to receive the hitch ball therein. Once the hitch ball is received within the ball receiver, a latch secures the ball receiver to the hitch ball.
This arrangement is very convenient in that it allows rapid swapping of hitch balls upon the mount arm in order to accommodate different sized hitch balls as may be needed to accommodate trailers with differing sized ball receivers. Additionally, the draw bar can be quickly removed from the tractor whenever towing of a trailer is not desired and attached back thereto whenever towing is desired.
Due to the forces exerted on the coupling mechanisms that couple the trailer to the tractor, the components that make up the hitch assembly and the ball receiver are made from relatively thick and solid metal materials. While such components assure a solid mechanical coupling of trailer to tractor, certain shortcomings have been noted. Forces exerted on the trailer during road travel are transferred to the tractor due to the solid mechanical coupling of the trailer to the tractor. Such forces are occasioned from tractor acceleration and deceleration, and bumps in the roadway. Such transfer of forces not only results in a relatively unpleasant ride for passengers of the tractor, but also leads to relatively rapid degradation of the coupling components. Not only does such rapid wear on the components result in a relatively short lifespan for the coupling systems, if left unchecked, a catastrophic failure can occur during travel, resulting in a potentially dangerous situation for passengers of the tractor as well as others on the road.
To address this problem, devices have been proposed that attenuate the force transfer between trailer and tractor. Such devices, which can be found in a variety of architectures and which operate with varying degrees of efficiency, absorb many of the forces exerted by the trailer during travel so that such forces are neither occasioned upon the trailer-tractor coupling system, nor the tractor proper. By dampening the forces caused by acceleration, deceleration, and road bumps, the wear and tear presented onto the coupling systems is reduced, thereby extending the life span of the systems and decreasing the likelihood of a catastrophic failure. Additionally, as the travel forces are absorbed by the dampening system, such forces are not transferred to the tractor, so that the passengers of the tractor enjoy a relatively more comfortable ride.
Although many tractor owners favor such dampening systems, such systems are not without shortcomings. Many such prior art devices are of relatively complex design and construction so that such devices are relatively expensive to manufacture, resulting in a relatively expensive end product. By being expensive, many potential consumers of such devices tend to forgo purchasing the devices. Additionally, the complexity of such devices requires a high level of maintenance in order to keep the devices operationally sound. This is especially true when the trailer being towed operates in relatively harsh environments such as construction sites or bodies of water. The owner is faced with the task of spending time and possibly money to keep the device properly maintained, or forgo the maintenance, potentially resulting in the undesirable premature failure of the system.
Accordingly, there exists a need in the art for a device that couples a trailer to a tractor and that avoids the above stated shortcomings found in the prior-art. Specifically, such a device must provide a solid mechanical coupling of the trailer to the tractor, yet must attenuate the travel forces experienced by the trailer so as to reduce the wear and tear upon the coupling system and to give the passengers of the tractor a relatively comfortable ride. Such a device must be of relatively simple design and construction so as to be relatively inexpensive to manufacture in order to allow the device to be economically feasible to a wide swath of potential consumers for the device. The device must be relatively easy to maintain.